nextjs - next build with NODE_ENV=development - reactjs

Question

I'd like to build my nextjs project as development mode.
and I tried like it
package.json
{
...
"scripts": {
"dev": "next",
"build:dev": "set NODE_ENV=development & next build",
"build:prod": "set NODE_ENV=production & next build",
"start:dev": "set NODE_ENV=development & next start",
"start:prod": "set NODE_ENV=production & next start"
}
...
}
next.config.js
module.exports = withSass({
env: {
baseUrl: process.env.NODE_ENV === "development" ? "devServerURL": "prodServerURL"
}
});
but I couldn't achieve what I want.
so, I tried with some change.
package.json
"scripts": {
"dev": "next",
"build": "next build",
"start:dev": "set NODE_ENV=development & next start",
"start:prod": "set NODE_ENV=production & next start"
}
but it also doesn't work.
How can I build the next with development mode?
Thanks in advance.
EDIT
My OS is Windows 10.

Answer 1

UPDATE 2022-11-23:
See how-to-set-environment-variables-from-within-package-json.
In short:
"start:dev": "NODE_ENV=development next start"
You might need cross-env (on Windows ? I don't know):
"start:dev": "cross-env NODE_ENV=development next start"
More specific documentation is now available (and maybe requirements also have changed, or maybe not):
environment-variable-load-order:
... Note: The allowed values for NODE_ENV are production, development and test.
non-standard-node-env:
... only permitting three (3) values:
production: When your application is built with next build
development: When your application is ran with next dev
test: When your application is being tested (e.g. jest)
ORIGINAL ANSWER:
See issue #9123, (Oct 18, 2019) :
NODE_ENV is a reserved environment variable that cannot be changed.
The only valid values are production, development, and test.
If you need your app behavior to change in different production
environments, please use a different variable like APP_ENV.
And issues #17032 (Sep 12, 2020):
process.env.NODE_ENV only has 2 possible values development and
production. If this is not set to that value you'll run into all kinds
of library edge cases (especially in node_modules) where you get
severely de-optimized results. E.g. if you run a performance test
you'll get significantly worse results if process.env.NODE_ENV is not
set to production

Answer 2

We solve it from our pipeline. Basically, when we build the image:
copy ".env.%ENVIROMENT%" to "./.env"
Then, if it finds a .env file, it always uses that.
You need to configure the value of %ENVIROMENT% in each pipeline you use for production or development (or make it recognize which pipeline it is).
If you have different steps during the image build, you could even use different environments for building and running.
Dockerfile example (this is not the best Dockerfile):
FROM node:16.17.3-buster-slim as build
WORKDIR /app
COPY package.json yarn.lock ./
COPY . ./
COPY .env.%ENVFILE_NEXT% ./.env
RUN yarn
RUN yarn build
FROM node:16.17.3-buster-slim as dst
WORKDIR /app
COPY --from=builder /app/.next ./.next
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package.json ./package.json
COPY --from=builder /app/public ./public
COPY --from=builder /app/next.config.js ./next.config.js
COPY --from=builder /app/next-i18next.config.js ./next-i18next.config.js
#
COPY .env.%ENVFILE_NEXT% ./.env
EXPOSE 3000
CMD ["yarn", "start"]